There are known methods for producing 1,6-GPS from sucrose that include enzymatic conversion of sucrose to isomaltulose followed by chemical hydrogenation of the resulting isomaltulose to the two stereoisomers 1,6-GPS and 1-0-α-D-glucopyranosyl-D-mannitol (1,1-GPM).
A sucrose isomerase that catalyzes the conversion of sucrose to isomaltulose is known from DE 44 14 185 C1.
Schiweck (alimenta 19 (1980), 5–16) discloses the enzymatic conversion of sucrose to isomaltulose and subsequent hydrogenation to the isomaltulose on Raney nickel catalyst to Palatinit® (also called isomalt), a nearly equimolar mixture of 1,6-GPS and 1,1-GPM. The publication describes the preparation of isomaltulose by transglucosidation of sucrose by Protaminobacter rubrum. In addition, how the isomaltulose produced by microorganisms is converted in the presence of Raney nickel catalysts to 1,6-GPS and 1,1-GPM by hydrogenation and can then be enriched by evaporation and cooling crystallizations is disclosed.
DE 197 01 439 A1 discloses a method for hydrogenation of isomaltulose by means of a carrier-bound nickel substrate, with mixtures of 1,6-GPS and 1,1-GPM being obtained.
DE 197 05 664 A1 describes a method for producing 1,6-GPS and 1,1-GPM enriched mixtures. This publication discloses a method in which 1,6-GPS and/or 1,1-GPM enriched mixtures are obtained from hydrogenated isomaltulose or from mixtures that contain hydrogenated isomaltulose. It is possible by means of this method to produce 1,6-GPS in pure form, by concentrating and cold-crystallizing 1,6-GPS-rich mother solution under certain conditions.
DE 195 23 008 A1 discloses a method for producing 1,1-GPM and 1,6-GPS. The document describes how various catalysts are used at pressures under 50 atmospheres so that mixtures of 1,6-GPS and 1,1-GPM are obtained by hydrogenation of isomaltulose. The disclosed catalyst on which the isomaltulose is converted contains ruthenium, nickel and their mixtures.
Methods for obtaining sugar alcohol mixtures containing 1,1-GPM and 1,6-GPS by enzymatic rearrangement of sucrose to isomaltulose and trehalulose and subsequent hydrogenation to 1,1-GPM, 1,6-GPS and 1-0-α-D-glucopyranosyl-D-sorbitol (1,1-GPS) follow from EP 0 625 578 B1.
The methods according to the prior art are seen as disadvantageous above all for two reasons. First, with the current methods one can only obtain mixtures of 1,6-GPS and 1,1-GPM, from which the substance of interest (1,6-GPS or 1,1 -GPM) then has to be isolated by costly chemical and physical separation methods. Second, it is not possible to conduct the overall process of converting sucrose to the desired end products in a single process step. Thus in the prior art quite complicated process sequences are necessary for the production of 1,6-GPS from sucrose, employing various physical, chemical and biological process steps in different reactors. Catalysts, special hydrogenation reactors and technical hydrogen are necessary according to the current state of the art for the hydrogenation of isomaltulose. An important disadvantage of the known hydrogenation of isomaltulose to 1,6-GPS and 1,1-GPM thus lies in the required industrial expenditure. Frequently, pressures of roughly 50 to over 100 atmospheres are necessary for the hydrogenation, which necessitates a specific equipment design. Since the resulting products are used as a rule in the food industry, the process operations additionally have to be chosen so that no toxic materials, for example the catalysts, get into the end products of the hydrogenation reaction. The product that is formed is a mixture of the important components 1,6-GPS and 1,1-GPM, from which the substance of interest in each case has to be separated by chemical and chemical-physical purification methods. To obtain chemically pure 1,6-GPS or 1,1-GPM, costly enrichment and isolation procedures are thus necessary after the chemical hydrogenation. The yield of these process steps is frequently unsatisfactory.
The industrial problem underlying this invention thus consists of making available a process and a means for conducting it that enable a simple, cheap and selective preparation of 1,6-GPS from isomaltulose.